System, methods, and apparatuses for managing data rate for control plane optimization

ABSTRACT

In one aspect, an MME throttles (or otherwise controls) the amount or frequency of UL data that a UE transmits in the control plane, such as by communicating to the UE rate control information (e.g., a throttling factor or throttling delay). For instance, the MME may throttle NAS messages with user data (i.e., NAS Data PDUs) sent using control plane CIoT EPS optimization by adding a throttling factor and/or a throttling delay in a NAS message sent to the UE.

TECHNICAL FIELD

This disclosure relates to a system, methods, and apparatuses formanaging data rate for control plane optimization.

BACKGROUND

3GPP is developing narrowband radio technology for facilitatingInternet-of-Things (IoT) communication using cellular networks. Thisdevelopment for communication includes data transmission for smallquantities of infrequent data, as specified in TS 45.820 and TR 23.720,version 1.2.0. This data may come from user equipments (UEs) that are,for example, low in complexity and power constrained. Such UEs aresometimes referred to as cellular IOT (CIoT) devices (e.g., indoorappliances, sensors, medical devices).

This development further includes the introduction of control plane CIoTEPS optimization, which provides for the transport of user data (a.k.a.,“uplink (UL) data”) in the evolved packet system (EPS) control plane, asspecified in a change request to TR 23.401 (CR 2942, or S2-160403). Thismay involve the transfer of user data in non-access stratum (NAS)signalling, and may be accomplished by using NAS transport capabilitiesof radio resource control (RRC) and S1-AP protocols and data transportbetween the mobility management entity (MME) and serving gateway (SGW)and packet data network gateway (PGW). In this context, a UE may sendpart of its uplink data in a manner that is encrypted and integrityprotected in a NAS message, which may be relayed to the MME. The MMEdecrypts the uplink (UL) data, and may send the UL data to the PGW viathe SGW.

SUMMARY

The present disclosure relates to controlling a data rate of data (e.g.,UL data) that is transported in the control plane. For instance, asensor or other CIoT device may include UL data in a control message(e.g., a NAS message—such a NAS message is referred to as a NAS DataProtocol Data Unit (PDU)) that is transmitted to a MME node in a LTEcore network. Sending the UL data in the control plane (e.g., in NASData PDU), however, involves potential adverse effects on controlsignaling that also uses the control plane (e.g., signaling used byother devices in establishing a radio resource control (RRC)connection). Thus, there is a need to limit the amount of data (e.g. ULdata) being sent on the control plane. This may include limiting thedata rate to, e.g., a maximum bit rate (MBR), aggregated maximum bitrate(AMBR), UE aggregated maximum bitrate (UE-AMBR), or UE control planeaggregated maximum bitrate (UE-CP-AMBR). The data rate needs to becontrolled for UL data from the UE and being relayed by the network(e.g. MME node, SCEF, SGW, or PGW), and also for DL data being relayedby the network to the UE. The DL data may be relayed by a SCEF node(which is described in TS 23.682, CR 0154, S2-160423 and S2-154024)toward a WCD. The DL data may have to pass through the MME node, andmore specifically may use the control plane for transport. Thistransmission of DL data thus still competes with radio resources thatcould be used for control signaling. Thus, there are advantages tocontrolling data rate for both UL and DL data for CIoT and other UEs.

This disclosure more specifically addresses UL data rate control betweena MME node and a UE, which are end points of the control plane, andaddresses DL data rate control between the MME node and a servicecapability exposure function (SCEF) node, which are endpoints of the T6ainterface.

For UL data rate control, the MME node may attempt to throttle (orotherwise control) the amount or frequency of UL data that a UEtransmits in the control plane, such as by communicating to the UE ratecontrol information (e.g., a throttling factor or throttling delay). Forinstance, the MME may throttle NAS messages with user data (i.e., NASData PDUs) sent using control plane CIoT EPS optimization by accepting aNAS message and adding a throttling factor and/or a throttling delay ina NAS message sent to the UE. The UE shall follow the throttling factorand/or throttling delay sent by the MME until the throttling has beenomitted in the next NAS message from the network, or the throttlingdelay time has expired. As an example, the UE may refrain from sendingany subsequent NAS message with user data using control plane CIoT EPSoptimization until a criterion (e.g., throttling delay) is fulfilled. Asanother example, the UE may reduce the amount of user data that it sendsin subsequent NAS messages, where the reduction amount is specified bythe throttling factor (e.g., as a percentage of the UL data beingtransmitted in the control plane during normal operation).

The UE may resume normal operation when the throttling delay hasexpired, or when the MME node communicates a subsequent control message(e.g., NAS message) in which the throttling factor and throttling delayare omitted. Alternatively, the MME node may also provide a newthrottling factor or throttling delay in a subsequent control message.The last received value of the throttling factor and throttling delaysupersedes any previous values received from that MME node. Thereception of a throttling delay may restart the UE throttling delaytimer.

According to one aspect of the present disclosure, a method and MME nodeis presented for managing signaling congestion. The method comprises theMME node receiving (e.g., accepting) a first control plane message(e.g., a non-access stratum (NAS) message, such as a NAS attach requestmessage) transmitted by the WCD, the first control plane messageincluding uplink (UL) data (e.g., user plane data) intended for relay bythe MME node to another device. After receiving the first controlmessage, the MME node creates a second control message (e.g., a NASattach accept message), the second control plane message identifying atleast one of: i) a throttling factor that indicates a level by which theWCD should reduce the amount of UL data in any future control planemessage to the MME node, and ii) a throttling delay that indicates howmuch time the WCD should wait before including any UL data in any futurecontrol plane message to the MME. The MME node then transmits the secondcontrol plane message including the at least one of the throttlingfactor and the throttling delay, the second control plane messageintended for the WCD.

According to one aspect of the present disclosure, a method and WCD ispresented for managing signaling congestion. In the method, the WCDtransmits a first control plane message which includes uplink (UL) dataintended for relay by a mobility management entity (MME) node to anotherdevice, the first control plane message intended for the MME node. TheWCD receives a second control plane message transmitted from a mobilitymanagement entity (MME) node, the second control plane message includingat least one of: i) a throttling factor that indicates a level by whichthe WCD should reduce the amount of UL data in any future control planemessage to the MME node and ii) a throttling delay that indicates howmuch time the WCD should wait before including any UL data in any futurecontrol plane message to the base station or to the MME. After receivingthe second control plane message, the WCD transmits a third controlplane message with an amount of UL data (e.g., zero amount of UL data)based on the throttling factor, or with zero amount of UL data if the atimer set based on the throttling delay has not yet expired, the thirdcontrol plane message intended for the MME node.

For DL data rate control, a MME node can limit the number or frequencyof data delivery requests directed toward it. The MME node can rejectNIDD Submit Request messages or to further offload the MME, the MME canrequest the SCEFs to selectively reduce the number of NIDD SubmitRequests it sends for downlink traffic according to a throttling factorand for a throttling delay specified in the NIDD Submit Downlink Ackmessage (or NIDD Submit Ack message). See TS 23.682 for correspondingSCEF logic. The SCEF shall not send any subsequent NIDD Submit Requestmessages with user data until its throttling delay timer has expired.The SCEF resumes normal operations at the expiry of the throttlingdelay. The last received value of the throttling factor and throttlingdelay supersedes any previous values received from the MME. Thereception of a throttling delay restarts the SCEF throttling delaytimer. In an alternative embodiment, the SCEF resumes normal operationwhen it receives a subsequent NIDD Submit Downlink Ack message (or NIDDSubmit Ack message) from the network where the throttling factor andthrottling delay has been omitted.

According to an aspect of the present disclosure, a method and MME nodeis presented for interacting with a service capability exposure function(SCEF) node and to one or more wireless communication devices (WCDs).The method comprises the MME node determining whether one or morethrottling criteria have been met (e.g., whether congestion of controlsignaling between the MME node and the one or more WCDs has deterioratedpast a predetermined threshold). In response to determining that the oneor more throttling criteria have been met (e.g., congestion of controlsignaling has deteriorated past the predetermined threshold): the MMEnode creating a first data delivery message (e.g., MT NIDD response orNIDD submit downlink ack message) that includes at least one of: i) athrottling factor that indicates a level by which the SCEF node shouldreduce the number of downlink (DL) data delivery requests to the MMEnode, and ii) a throttling delay that indicates how much time the SCEFnode should wait before transmitting any future data delivery request tothe MME node. The MME node transmitting the first data delivery messageincluding the at least one of the throttling factor and the throttlingdelay, the first data delivery message intended for the SCEF node.

According to an aspect of the present disclosure, a SCEF is presentedfor managing congestion. In the method, the SCEF receives a first datadelivery message (e.g., NIDD submission ack message or MT NIDD responsemessage) transmitted by a mobility management entity (MME) node, thefirst data delivery message including at least one of: i) a throttlingfactor that indicates a level by which the SCEF node should reduce thenumber of downlink (DL) data delivery requests to the MME node, and ii)a throttling delay that indicates how much time the SCEF node shouldwait before transmitting any future data delivery request to the MMEnode. After receiving the second control plane message, the SCEFreducing the number of data delivery requests transmitted to the MMEnode based on the throttling factor, or refraining from transmitting anydata delivery request to the MME node if a timer based on the throttlingdelay has not yet expired.

Further, the MME can request a base station (e.g., eNB) to reject newRRC connection requests from UEs that access the network to send userdata via the Control Plane for normal priority and/or exceptionreporting.

In another aspect, there is provided a rate control method performed byan MME. In one embodiment, the method includes the MME receiving an ULNAS message (e.g., attach request) transmitted by a WCD. The methodfurther includes the MME, after receiving the UL NAS message, generatinga DL NAS message and transmitting the DL NAS message towards the WCD.The DL NAS message transmitted by the MME comprises informationindicating a number of UL NAS messages containing user data that the WCDis permitted send to the MME within a certain time period. In someembodiments, the number of UL NAS messages indicated by the informationincluded in the DL NAS message is zero. In some embodiments, the DL NASmessage transmitted by the MME comprises information indicating thecertain time period. In some embodiments, the UL NAS message transmittedby the WCD comprises user data, and the method further comprises the MMEforwarding the user data to another device. In some embodiments, themethod further includes the MME receiving a second UL NAS messagetransmitted by the WCD, wherein the second UL NAS message comprises userdata intended for another device; and the MME discarding the user datasuch that the MME does not forward the user data to the another device.

In another aspect, there is provided a method for CN overload control.In one embodiment, the method includes a network node (e.g., MME)determining that a load has reached a threshold. The method furtherincludes, after determining that the load has reached the threshold, thenetwork node transmitting to a base station an Overload Start messagecomprising information for configuring the base station such that thebase station rejects a request transmitted by a WCD for data transfervia control plane CIoT EPS Optimization.

In another aspect, there is provided a method for CN overload control.In one embodiment, the method includes a base station receiving from anetwork node (e.g., MME) an Overload Start message comprisinginformation indicating that the base station may reject a request fordata transfer via control plane CIoT EPS Optimization. The methodfurther includes, after receiving the Overload Start message, the basestation receiving from a WCD a request for data transfer via controlplane CIoT EPS Optimization. The method further includes, in response toreceiving the request transmitted by the WCD, the base station rejectingthe request.

These and other aspects and embodiments are further described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-2 illustrate an example system according to an aspect of thepresent disclosure.

FIGS. 3-11 provide flow diagrams and signaling diagrams that illustratesaspects of the present disclosure.

FIG. 12 illustrates an example MME node configured to manage congestion,according to aspects of the present disclosure.

FIG. 13 illustrates an example UE configured to manage congestion,according to aspects of the present disclosure.

FIG. 14 illustrates an example SCEF node configured to managecongestion, according to aspects of the present disclosure.

FIG. 15 illustrates an example base station configured to managecongestion, according to aspects of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates an example system 100 for managing congestion andmanaging UL and DL data that may be transmitted in a control plane. Thesystem 100 includes one or more wireless communication devices (WCDs),such as user equipment (UE) 101. It further includes a base station,such as NB/eNB 103, a mobility management entity (MME) node 105, aservice capability exposure function (SCEF) node 107, a serving gateway(SGW) 111, a PDN gateway (PGW) 113, a PCRF 115, a HSS 117, and anapplication server 109.

In some cases, the UE may be a cellular Internet of Things (CIoT)device, such as a sensor or appliance. Compared to a UE such as asmartphone, a sensor or appliance may transmit (e.g., broadcast) muchless UL data and do so much less frequently. Under some circumstances,it may be more efficient to transmit such UL data in the control planerather than in the user plane. The control plane may include, forexample, the non-access stratum (NAS) layer used by the UE 101 and theMME 105 to communicate with each other. The data may include UL datatransmitted by the UE 101 for another device (e.g., application server109) or DL data transmitted by another device (e.g., AS 109) for UE 101.The data, in some situations, are transported using non-IP data delivery(NIDD), as specified in TS 23.682 (see change request 0154, orS2-160423). The SCEF node 107, which is also described in TS 23.682, mayfacilitate delivery of non-IP data.

FIG. 2 illustrates a more specific example of system 100. In thisexample, the SCEF node 107 may be part of a services capability server(SCS) and/or a machine-type communication (MTC) Interworking function(MTC-IWF) node. In other instances, the SCEF node 107 may be astandalone component. The SCEF node 107 may be located at an edge of thecore network and act as a gateway to devices outside the core network.Additionally, while FIG. 1 and FIG. 2 show a MME node 105, thefunctionality and steps performed in the MME node 105 may in someembodiments be performed in a CIoT service gateway node (C-SGN), eitherin addition to or as an alternative to the MME node 105.

As discussed above, UL and DL data for a UE that is a CIoT device may bemore efficiently transmitted in the control plane between the UE 101 andMME 105, and via NIDD between the MME 105 and the application server 109or other source or destination of the data. The control plane may have alimited amount of transmission resources, such as radio transmissionresources (e.g., frequency and time resources) used by the UE 101 andeNB/NB 103 to wirelessly exchange information. The transport of the ULand DL data in the control plane may compete with control signaling forsuch transmission resources. As a result, it may significantly interferewith control signaling between the MME 105 and the UE 101, and/orbetween the eNB/NB 103 and the UE 101.

Thus, methods are needed to perform rate control for UL data that the UEmay attempt to send in the control plane and for DL data that may beintended to be sent to the UE in the control plane.

UL Data Rate Control

For performing rate control for UL data, the MME may throttle NASmessages with user data (i.e., NAS Data PDUs) sent using Control PlaneCIoT EPS optimization (e.g., the MME may send a message to a UEindicating a time period (a.k.a., “throttling delay”) and indicating(implicitly or expressly) a number of NAS Data PDUs that the UE ispermitted to send during the indicated time period) by, for example,accepting the NAS message and adding a throttling factor and/or athrottling delay in a NAS message sent to the UE. The UE shall followthe throttling factor and throttling delay sent by the MME until thethrottling has been omitted in the next NAS message from the network, orthe throttling delay time has expired. (That is, for example, the UEshall not send any subsequent NAS messages with user data sent usingControl Plane CIoT EPS optimization until that criterion is fulfilled.)

The UE may resume normal operations at the expiry of the throttlingdelay. The last received value of the throttling factor and throttlingdelay supersedes any previous values received from that MME. Thereception of a throttling delay restarts the UE throttling delay timer.In an alternative embodiment, the UE resumes normal operation when theUE receives a subsequent NAS message from the network where thethrottling factor and throttling delay has been omitted. The detectionof NAS level congestion is discussed in more detail in section4.3.7.4.2.1 of TS 23.401, and is reproduced later in the disclosure.

FIGS. 3 and 4 provide flow diagrams that also illustrate coordinationbetween a MME node (e.g., MME node 105) and a wireless communicationdevice (e.g., UE 101) for limiting UL data rate and managing signallingcongestion between the MME node and the UE.

In an embodiment, the process 300 in FIG. 3 may begin in step 302, inwhich the MME node receives (e.g., accepting) a first control planemessage (e.g., a non-access stratum (NAS) message, such as a NAS attachrequest message) transmitted by the WCD, the first control plane messageincluding uplink (UL) data (e.g., user plane data) intended for relay bythe MME node to another device. Examples of the control plane messageinclude a NAS message that contains Control Plane CIoT Optimization data(or “small data”) (e.g. “NIDD Delivery” message). Other examples,depending on protocol layer, are “S1-AP Initial UE Message (NAS Data PDUwith EBI)” or “Uplink S1-AP msg (NAS Data PDU with EBI)”.

In step 306, after receiving the first control message, the MME node maycreate a second control message (e.g., a NAS attach accept message), thesecond control plane message identifying at least one of: i) athrottling factor that indicates a level by which the WCD should reducethe amount of UL data in any future control plane message to the MMEnode, and ii) a throttling delay that indicates how much time the WCDshould wait before including any UL data in any future control planemessage to the MME (i.e., the second control plane message may indicatea time period (i.e., “throttling delay”) (e.g., 0.5 deci hours) and anumber of NAS Data PDUs that the UE is permitted to send during theindicated time period, wherein, in this example, the number is zero).

In step 308, MME node transmits the second control plane messageincluding the at least one of the throttling factor and the throttlingdelay, the second control plane message intended for the WCD. Forinstance, the MME node may transmit the second control plane messagetoward the WCD, via a base station between the two nodes. Examples ofthis message include a Downlink S1-AP message with a DL NAS message thatincludes the throttling factor and throttling delay.

FIG. 3 further illustrates an optional step 304 for process 300. In step304, the MME node may determine in step 304 whether congestion ofcontrol signaling between the MME node and the WCD has deteriorated pasta predetermined threshold. In this example, step 306 may be performed inresponse to both receiving first control plane message from the WCD anddetermining that congestion has deteriorated past the predeterminedthreshold.

In some cases, the received control plane message (e.g., NAS message)may be processed (i.e. forwarded UL data or be discarded). Throttlingcan also be initiated at a later stage when congestion/overload has beendetected (but before the signaling connection with the UE is released).Immediate initiation of the throttling may be done if thecongestion/overload has already been detected in the MME when the UL NASmessage is received

In some instances, the MME node may initiate the throttling processimmediately after receiving a control plane message (e.g., in step 302)transmitted by the WCD. In some instances, it may do so without firstreceiving a control plane message from the WCD, and may instead initiatethe throttling criteria based on some other throttling criterion orcriteria, such as a result of overload/congestion, and/or as a result ofthat the UE has exceeded its small data quota, subscribed maximumbitrate, subscribed maximum bitrate for the Control Plane, exceededService Level Agreement etc. In some instances, a combination of thesecriteria may need to be satisfied (e.g., the MME node has to receive acontrol plane message and detect control signaling congestion, and/ordetect that the WCD has exceeded a maximum UL bit rate or quota) beforethe MME node will initiate the throttling process.

In some instances, the MME node may determine whether the WCD hasexceeded a predetermined maximum data quota or maximum data rate (e.g.,subscribed maximum bit rate, subscribed UE aggregated maximum bit ratefor the CP or totally for the UE), wherein the step of transmitting thesecond control plane message including the throttling factor or thethrottling delay is performed in response to receiving first controlplane message from the WCD and determining that the WCD has exceeded apredetermined maximum data quota or maximum data rate.

More generally speaking, the receipt of the first control plane messagewith the uplink data in step 302, the deterioration of congestion past athreshold, and/or the exceeding of the maximum bit rate (e.g., maximumUL bit rate) may be examples of throttling criteria. The MME node maythus trigger throttling when one or more of the throttling criteria aremet. This is illustrated in a process in FIG. 4, in which the MME node,in step 402, determines whether one or more throttling criteria havebeen met. The MME node in this embodiment may transmit the secondcontrol plane message that includes the throttling factor or throttlingdelay in step 308 without first waiting to receive a control planemessage with UL data from the WCD. In that instance, the throttling maybe triggered by deterioration of signaling congestion at the MME nodeand/or the WCD exceeding a maximum bit rate or UL data quota.

The throttling factor or throttling delay transmitted in step 308 may beoverridden. FIG. 3 illustrates the overriding feature with step 312, inwhich, after transmitting the second control plane message, the MME nodetransmits a third control plane message which includes anotherthrottling factor or another throttling delay, wherein the otherthrottling delay overrides the throttling delay in the second controlplane message and the other throttling factor overrides the throttlingfactor in the second control plane message.

As discussed above, the UE may stop the throttling when a timer set by athrottling delay (if transmitted) expires, or when the UE receives asubsequent control plane message that the throttling can cease. In step312, for example, after transmitting the second control plane message,for instance, the MME node may transmit a third control plane messagewhich includes no throttling factor and no throttling delay, wherein theomission of the throttling factor and the throttling delay is anindication that the one or more WCDs can stop throttling UL data incontrol plane messages.

In some cases, the throttling factor may indicate that the WCD shouldinclude no UL data in any future control plane message to the MME nodeuntil the MME node indicates stopping of throttling. In some cases, thethrottling factor may indicate a percentage (e.g., 25, 50, 100%) bywhich the WCD should reduce UL data transmission in the control plane.

In some instances, the MME node determines a maximum bit rate (MBR) atwhich to limit UL data in the control plane between the MME node and oneor more WCDs attached to the MME node. The MME may determine thethrottling factor or the throttling delay based on the determined MBR.

FIG. 5 illustrates data rate control from the perspective of the WCD.The process 500 illustrated in FIG. 5 may, in one embodiment, begin atstep 502, in which the WCD transmits a first control plane message whichincludes uplink (UL) data intended for relay by a mobility managemententity (MME) node to another device, the first control plane messageintended for the MME node. For instance, the WCD may transmit thecontrol plane message toward the MME node, via a base station betweenthe two nodes.

In step 504, the WCD receives a second control plane message transmittedfrom a mobility management entity (MME) node, the second control planemessage including at least one of: i) a throttling factor that indicatesa level by which the WCD should reduce the amount of UL data in anyfuture control plane message to the MME node and ii) a throttling delaythat indicates how much time the WCD should wait before including any ULdata in any future control plane message to the base station or to theMME.

In step 506, after receiving the second control plane message, the WCDtransmits a third control plane message with an amount of UL data (e.g.,zero amount of UL data) based on the throttling factor, or with zeroamount of UL data if the a timer set based on the throttling delay hasnot yet expired, the third control plane message intended for the MMEnode. This step may be part of the WCD's efforts to throttle itstransmission of UL data in the control plane.

In an embodiment, the WCD may receive, in step 508, a third controlplane message transmitted by the MME node that includes anotherthrottling factor or another throttling delay which overrides those inthe earlier control plane message.

In an embodiment, the WCD may receive, in step 510, a third controlplane message which includes no throttling factor and no throttlingdelay. The WCD may identify this as an indication that it can stopthrottling of UL data in the control plane.

FIG. 6 provides a signaling diagram of the UL data rate control.Messages 601 and 602 show that the control plane message can be a NASmessage (e.g., NAS attach request message, as discussed in section 9.8of TS 24.301 included as a payload in a RRC message between a UE and abase station, and as a payload in a S1-AP message between the basestation and the MME node. In the illustrated embodiment, the MME nodemay initiate throttling after determining in step 604 that there iscontrol signaling congestion. It may transmit a NAS message usingmessages 605 and 606 to convey a throttling factor or throttling delayto the UE, which throttles UL data in step 607. The MME node may furthertransmit messages 608 and 609 to modify the throttling, or messages 610and 611 to stop the throttling. After the throttling is stopped, the UEmay resume normal transmission of UL data to the MME node in a controlplane (e.g., in the NAS layer).

DL Data Rate Control

DL data rate control may involve the MME rejecting data deliveryrequests (e.g., MT NIDD delivery request or NIDD submission request).Such requests may include DL data that may need to be relayed to a WCDin the control plane. Because this DL data may compete with controlsignaling for radio transmission resources, the DL data may bethrottled. The MME node may itself receive and reject individual datadelivery requests, or it may offload some of that gateway functionalityto the SCEF node. For instance, the MME can reject NIDD Submit Requestmessages or to further offload the MME, the MME can request the SCEFs toselectively reduce the number of NIDD Submit Requests it sends fordownlink traffic according to a throttling factor and for a throttlingdelay specified in the NIDD Submit Downlink Ack message (or NIDD SubmitAck message). See TS 23.682 for corresponding SCEF logic.

The SCEF shall not send any subsequent NIDD Submit Request messages withuser data until its throttling delay timer has expired. The SCEF resumesnormal operations at the expiry of the throttling delay. The lastreceived value of the throttling factor and throttling delay supersedesany previous values received from the MME. The reception of a throttlingdelay restarts the SCEF throttling delay timer. In an alternativeembodiment, the SCEF resumes normal operation when it receives asubsequent NIDD Submit Downlink Ack message (or NIDD Submit Ack message)from the network where the throttling factor and throttling delay hasbeen omitted. In some instances, the MME node may also restrictsignaling node that its SGW may generate, by throttling downlink datanotification requests from the SGW. Throttling downlink datanotification requests from the SGW is discussed in TS 23.401, section4.3.7.4.1a, which is also reproduced below.

FIG. 7 illustrates another example of DL data rate control. In theprocess 700 illustrated in FIG. 7, the MME node may, in step 702,determine whether one or more throttling criteria have been met. The oneor more criteria may include, for instance, receipt of a data deliveryrequest message (e.g., MT NIDD delivery request or NIDD submissionrequest) transmitted by the SCEF node, congestion of control signalingbetween the MME node and one or more WCDs has deteriorated past apredetermined threshold, and/or the one or more WCDs exceeding a maximumbit rate (e.g., a maximum DL bit rate) or DL data quota (which may bepredetermined values set by a network operator, or may be dynamicallydetermined).

In step 704, in response to a determination that the one or morethrottling criteria have been met, the MME node may create a first datadelivery message (e.g., MT NIDD response or NIDD submit downlink ackmessage) that includes at least one of: i) a throttling factor thatindicates a level by which the SCEF node should reduce the number ofdownlink (DL) data delivery requests to the MME node, and ii) athrottling delay that indicates how much time the SCEF node should waitbefore transmitting any future data delivery request to the MME node. Insome cases, the throttling factor or the throttling delay may be basedon a determined maximum bit rate at which the MME node is attempting tolimit for one or more WCDs.

In step 706, the MME node may transmit the first data delivery messageincluding the at least one of the throttling factor and the throttlingdelay, the first data delivery message intended for the SCEF node. FIG.7 further illustrates steps 708 and 710 for modifying the throttling andstopping the throttling, respectively.

In some cases, the MME node may send the throttling factor or throttlingdelay in an empty NIDD response message or as a new message that iscreated for the purpose of DL data control between the MME node and theSCEF node. Note that if the throttling criteria does not involve the MMEnode first receiving a NIDD request message (e.g., MT NIDD requestmessage or NIDD submit request message) from the SCEF node, then thethrottling indication from the MME node may be sent to the SCEF node inan unsolicited manner.

FIG. 8 illustrates the DL data rate control from the perspective of theSCEF node. In step 802, the SCEF node receives a first data deliverymessage (e.g., NIDD submission ack message or MT NIDD response message)transmitted by a mobility management entity (MME) node, the first datadelivery message including at least one of: i) a throttling factor thatindicates a level by which the SCEF node should reduce the number ofdownlink (DL) data delivery requests to the MME node, and ii) athrottling delay that indicates how much time the SCEF node should waitbefore transmitting any future data delivery request to the MME node.

In step 804, after receiving the second control plane message, the SCEFreduces the number of data delivery requests transmitted to the MME nodebased on the throttling factor, or refraining from transmitting any datadelivery request to the MME node if a timer based on the throttlingdelay has not yet expired.

In an embodiment, the SCEF node may receive subsequent data deliverymessages from the MME node that modifies the throttling or indicatesthat the throttling can cease.

The DL rate control is also illustrated in the signal diagram in FIG. 9.In this particular example, the throttling may be initiated after theMME node receives a NIDD submission request message 903 that includes DLnon-IP data. The non-IP data may originate from, for example a servicescapability server (SCS) and/or an application server (AS), whichdetermines in step 901 that non-IP data exists and transmits a NIDDsubmission request message 902 to the SCEF node.

To initiate throttling, the MME node may transmit a NIDD submissiondownlink ack message 904 with a throttling factor or throttling delay tothe SCEF node. This causes the SCEF node, even after receiving non-IPdata in step 905, to throttle NIDD submission request messages in step906. The throttling may be modified in message 907, and may be stoppedby the MME node in step 908. After the throttling is stopped, the SCEFnode may continue to forward NIDD submission request to the MME node,which may then relay the DL data toward the UE in the user plane or thedata plane.

Coordination Between MME Node and Base Station

Rate control (e.g., UL data rate control) may also involve the MME nodecoordinating with a base station to limit network access (e.g., RANaccess) if that access may involve transmission of excessive UL in thecontrol plane. This coordination allows a MME node to make a request toa base station for all UEs that are camped on a base station and usingthe control plane to transport data. In one example, the MME node mayuse an Overload Start message, which is discussed in TS 23.401, atsection 4.3.7.4.1, which is also reproduced below. In the example, theMME node may use the Overload Start message to request an eNB to rejectnew RRC connection requests from UEs that access the network to senduser data via the Control Plane for normal priority and/or exceptionreporting.

FIG. 10 illustrates another example of an overload handling mechanismthat involves coordination between a MME node and base station. Thisexample includes a process 1000 that begins, in an embodiment, in step1002, in which the MME node determines whether congestion of controlsignaling between the MME node and the one or more WCDs has deterioratedpast a predetermined threshold. In step 1006, in response to determiningthat the congestion has deteriorated past the predetermined threshold,the MME node generates an overload start message that indicates the basestation should reject any radio resource control (RRC) connectionrequests being used by a WCD to access the MME node to send uplink (UL)data in a control plane message (i.e., a request from the WCD for datatransfer via control plane CIoT EPS Optimization).

In step 1008, the MME node transmitting the overload start message tothe base station.

FIG. 11 illustrates a process 1100 that is from the perspective of thebase station. In step 1102, the base station receives an overload startmessage transmitted by the MME node, the message indicating the basestation should reject any radio resource control (RRC) connectionrequests being used by a WCD to access the MME node to send uplink (UL)data in a control plane message (i.e., a request from the WCD for datatransfer via control plane CIoT EPS Optimization).

In step 1104, after receiving the overload start message, the basestation receives a RRC connection request from one of the WCDs, the RRCconnection request including a control plane message (i.e., the requestis a request for data transfer via control plane CIoT EPS Optimization).In step 1106, the base station determines whether the control planemessage includes UL data. In step 1108, in response to determining thatthe control plane message includes UL data, the base station rejectingthe RRC connection request. In some instances, the information forwhether the control plane message includes UL data may be in the headerof the RRC connection request.

Exemplary MME Node

FIG. 12 illustrates a block diagram of an example MME node 105. As shownin FIG. 12, the interference mitigation controller may include: a dataprocessing system 1202, which may include one or more processors 1255(e.g., microprocessors and/or one or more circuits, such as anapplication specific integrated circuit (ASIC), Field-programmable gatearrays (FPGAs), etc.); a communication interface 1205 for communicatingwith the RAN and an interface 1205 for communicating with a SCEF node, adata storage system 1206, which may include one or morecomputer-readable data storage mediums, such as non-transitory datastorage apparatuses (e.g., hard drive, flash memory, optical disk, etc.)and/or volatile storage apparatuses (e.g., dynamic random access memory(DRAM)). In embodiments where data processing system 1202 includes aprocessor (e.g., a microprocessor), a computer program product 1233 maybe provided, which computer program product includes: computer readableprogram code 1243 (e.g., instructions), which implements a computerprogram, stored on a computer readable medium 1242 of data storagesystem 1206, such as, but not limited, to magnetic media (e.g., a harddisk), optical media (e.g., a DVD), memory devices (e.g., random accessmemory), etc. In some embodiments, computer readable program code 1243is configured such that, when executed by data processing system 1202,code 1243 causes the data processing system 1202 to perform stepsdescribed herein. In some embodiments, the MME node may be configured toperform steps described above without the need for code. For example,data processing system 1202 may consist merely of specialized hardware,such as one or more application-specific integrated circuits (ASICs).Hence, the features of the present invention described above may beimplemented in hardware and/or software.

Exemplary Wireless Communication Device (WCD)

FIG. 13 illustrates a block diagram of an example of the WCD 106. Asshown in FIG. 16, WCD 106 may include: the data processing system (DPS)1602 (which includes, e.g., a digital signal processor (DSP), which mayinclude one or more processors (P) 1655 (e.g., microprocessors) and/orone or more circuits, such as an application specific integrated circuit(ASIC), Field-programmable gate arrays (FPGAs), etc.; a transceiver1605, each connected to an antenna 1622, for wirelessly transmitting andreceiving information, respectively; a data storage system 1606, whichmay include one or more computer-readable data storage mediums, such asnon-transitory memory unit (e.g., hard drive, flash memory, opticaldisk, etc.) and/or volatile storage apparatuses (e.g., dynamic randomaccess memory (DRAM)).

In embodiments where data processing system 1602 includes a processor1655 (e.g., a microprocessor), a computer program product 1633 may beprovided, which computer program product includes: computer readableprogram code 1643 (e.g., instructions), which implements a computerprogram, stored on a computer readable medium 1642 of data storagesystem 1606, such as, but not limited, to magnetic media (e.g., a harddisk), optical media (e.g., a DVD), memory devices (e.g., random accessmemory), etc. In some embodiments, computer readable program code 1643is configured such that, when executed by data processing system 1602,code 1643 causes the data processing system 1602 to perform stepsdescribed herein.

In some embodiments, WCD 106 is configured to perform steps describedabove without the need for code 1643. For example, data processingsystem 1602 may consist merely of specialized hardware, such as one ormore application-specific integrated circuits (ASICs). Hence, thefeatures of the present invention described above may be implemented inhardware and/or software. For example, in some embodiments, thefunctional components of WCD 106 described above may be implemented bydata processing system 1602 executing program code 1643, by dataprocessing system 1601 operating independent of any computer programcode 1643, or by any suitable combination of hardware and/or software.In a second embodiment, WCD 106 further includes: 1) a display screencoupled to the data processing system 1602 that enables the dataprocessing system 1602 to display information to a user of WCD 106; 2) aspeaker coupled to the data processing system 1602 that enables the dataprocessing system 1602 to output audio to the user of UE 1602; and 3) amicrophone coupled to the data processing system 1602 that enables thedata processing system 1602 to receive audio from the user.

Exemplary SCEF Node

FIG. 14 illustrates a block diagram of an example of a SCEF node 107. Asshown in FIG. 14, the interference mitigation controller may include: adata processing system 1702, which may include one or more processors1455 (e.g., microprocessors and/or one or more circuits, such as anapplication specific integrated circuit (ASIC), Field-programmable gatearrays (FPGAs), etc.); a communication interface 1405 for communicatingwith the MME; a network interface 1403 for interfacing with a SCS/AS109, a data storage system 1406, which may include one or morecomputer-readable data storage mediums, such as non-transitory datastorage apparatuses (e.g., hard drive, flash memory, optical disk, etc.)and/or volatile storage apparatuses (e.g., dynamic random access memory(DRAM)). In embodiments where data processing system 1402 includes aprocessor (e.g., a microprocessor), a computer program product 1433 maybe provided, which computer program product includes: computer readableprogram code 1443 (e.g., instructions), which implements a computerprogram, stored on a computer readable medium 1442 of data storagesystem 1406, such as, but not limited, to magnetic media (e.g., a harddisk), optical media (e.g., a DVD), memory devices (e.g., random accessmemory), etc. In some embodiments, computer readable program code 1443is configured such that, when executed by data processing system 1402,code 1443 causes the data processing system 1402 to perform stepsdescribed herein. In some embodiments, SCEF node may be configured toperform steps described above without the need for code 1443. Forexample, data processing system 1402 may consist merely of specializedhardware, such as one or more application-specific integrated circuits(ASICs). Hence, the features of the present invention described abovemay be implemented in hardware and/or software.

Exemplary Base Station

FIG. 15 is a block diagram of an embodiment of a base station. As shownin FIG. 15, the base station (e.g., eNB/NB 103) may include: a computersystem (CS) 1502, which may include one or more processors 1555 (e.g., ageneral purpose microprocessor and/or one or more other data processingcircuits, such as an application specific integrated circuit (ASIC),field-programmable gate arrays (FPGAs), and the like); a networkinterface 1505 for use in connecting the network node to a network(e.g., core network) and communicating with other units connected to thenetwork; a transceiver 1507 coupled to an antenna 1508 for wirelesslycommunicating with WCDs; and a data storage system 1506 for storinginformation (e.g., network slice information received from networkmanagement node (e.g., NM or DM), which may include one or morenon-volatile storage devices and/or one or more volatile storage devices(e.g., random access memory (RAM)). In embodiments where computer system1502 includes a general purpose microprocessor, a computer programproduct (CPP) 1541 may be provided. CPP 1541 includes a computerreadable medium (CRM) 1542 storing a computer program (CP) 1543comprising computer readable instructions (CRI) 1544. CRM 1542 may be anon-transitory computer readable medium (i.e., magnetic media (e.g., ahard disk), optical media (e.g., a DVD), flash memory, and the like). Insome embodiments, the CRI 1544 of computer program 1543 is configuredsuch that when executed by data processing system 1502, the CRI causesthe computer system to perform steps described herein. In otherembodiments, computer system 1502 may consist merely of one or moreASICs. Hence, the features of the embodiments described herein may beimplemented in hardware and/or software.

TS 23.401 4.3.7.4.2.1 General

NAS level congestion control contains the functions: “APN basedcongestion control” and “General NAS level Mobility Management control”.

The use of the APN based congestion control is for avoiding and handlingof EMM and ESM signalling congestion associated with UEs with aparticular APN. Both UEs and network shall support the functions toprovide APN based EMM and ESM congestion control.

The MME may detect the NAS signalling congestion associated with the APNand start and stop performing the APN based congestion control based oncriteria such as: Maximum number of active EPS bearers per APN; Maximumrate of EPS Bearer activations per APN; One or multiple PDN GWs of anAPN are not reachable or indicated congestion to the MME; Maximum rateof MM signalling requests associated with the devices with a particularsubscribed APN; and/or Setting in network management.

The MME may detect the NAS signalling congestion associated with the UEsbelonging to a particular group. The MME may start and stop performingthe group specific NAS level congestion control based on criteria suchas: Maximum rate of MM and SM signalling requests associated with thedevices of a particular group; and/or Setting in network management.

The MME may detect the NAS signalling congestion associated with the UEsthat belong to a particular group and are subscribed to a particularAPN. The MME may start and stop performing the APN and group specificNAS level congestion control based on criteria such as: Maximum numberof active EPS bearers per group and APN; Maximum rate of MM and SMsignalling requests associated with the devices of a particular groupand a particular subscribed APN; and/or Setting in network management.

The MME should not apply NAS level congestion control for high priorityaccess and emergency services.

With General NAS level Mobility Management control, the MME may also usethe reject of NAS level Mobility Management signalling requests undergeneral congestion conditions.

TS 23.401 4.3.7.4.1a Throttling of Downlink Data Notification Requests

Under unusual circumstances (e.g. when the MME load exceeds an operatorconfigured threshold), the MME may restrict the signalling load that itsSGWs are generating on it, if configured to do so.

The MME can reject Downlink Data Notification requests for non-prioritytraffic for UEs in idle mode or to further offload the MME, the MME canrequest the SGWs to selectively reduce the number of Downlink DataNotification requests it sends for downlink non-priority trafficreceived for UEs in idle mode according to a throttling factor and for athrottling delay specified in the Downlink Data Notification Ackmessage.

The SGW determines whether a bearer is to be subjected to the throttlingof Downlink Data Notification Requests on the basis of the bearer's ARPpriority level and operator policy (i.e. operator's configuration in theSGW of the ARP priority levels to be considered as priority ornon-priority traffic). While throttling, the SGW shall throttle theDownlink Data Notification Requests for low and normal priority bearersby their priority. The MME determines whether a Downlink DataNotification request is priority or non-priority traffic on the basis ofthe ARP priority level that was received from the SGW and operatorpolicy.

If ISR is not active for the UE, during the throttling delay, the SGWdrops downlink packets received on all its non-priority bearers for UEsknown as not user plane connected (i.e. the SGW context data indicatesno downlink user plane TEID) served by that MME in proportion to thethrottling factor, and sends a Downlink Data Notification message to theMME only for the non throttled bearers.

If ISR is active for the UE, during the throttling delay, the SGW doesnot send DDN to the MME and only sends the DDN to the SGSN. If both MMEand SGSN are requesting load reduction, the SGW drops downlink packetsreceived on all its non-priority bearers for UEs known as not user planeconnected (i.e. the SGW context data indicates no downlink user planeTEID) in proportion to the throttling factors.

The SGW resumes normal operations at the expiry of the throttling delay.The last received value of the throttling factor and throttling delaysupersedes any previous values received from that MME. The reception ofa throttling delay restarts the SGW timer associated with that MME.

TS 23.401 4.3.7.4 MME Control of Overload 4.3.7.4.1 General

The MME shall contain mechanisms for avoiding and handling overloadsituations. These can include the use of NAS signalling to reject NASrequests from UEs.

In addition, under unusual circumstances, the MME shall restrict theload that its eNBs are generating on it if it is configured to enablethe overload restriction. This can be achieved by the MME invoking theS1 interface overload procedure (see TS 36.300 [5] and TS 36.413 [36])to all or to a proportion of the eNBs with which the MME has S1interface connections. To reflect the amount of load that the MME wishesto reduce, the MME can adjust the proportion of eNBs which are sent S1interface OVERLOAD START message, and the content of the OVERLOAD STARTmessage.

The MME should select the eNBs at random (so that if two MMEs within apool area are overloaded, they do not both send OVERLOAD START messagesto exactly the same set of eNBs).

The MME may optionally include a Traffic Load Reduction Indication inthe OVERLOAD START message. In this case the eNB shall, if supported,reduce the type of traffic indicated according the requested percentage(see TS 36.413 [36]) (The MME implementation may need to take intoaccount the fact that eNBs compliant to Release 9 and earlier version ofthe specifications do not support the percentage overload indication).

Using the OVERLOAD START message, the MME can request the eNB to: rejectRRC connection requests that are for non-emergency and non-high prioritymobile originated services (This blocks PS service and service providedby MSC following an EPS/IMSI attach procedure); reject new RRCconnection requests for EPS Mobility Management signalling (e.g. for TAUpdates) for that MME; only permit RRC connection requests for emergencysessions and mobile terminated services for that MME. This blocksemergency session requests from UEs with USIMs provisioned with AccessClasses 11 and 15 when they are in their HPLMN/EHPLMN and from UEs withUSIMs provisioned with Access Classes 12, 13 and 14 when they are intheir home country (defined as the MCC part of the IMSI, see TS 22.011[67]) (The MME can restrict the number of responses to paging by notsending paging messages for a proportion of the events that initiatepaging. As part of this process, the MME can provide preference forpaging UEs with Emergency Bearer Services and terminations associatedwith MPS ARP); only permit RRC connection requests for high prioritysessions and mobile terminated services for that MME; reject new RRCconnection requests from UEs that access the network with low accesspriority.

When rejecting an RRC connection request for overload reasons the eNBindicates to the UE an appropriate timer value that limits further RRCconnection requests for a while.

An eNB supports rejecting of RRC connection establishments for certainUEs as specified in TS 36.331 [37]. Additionally, an eNB providessupport for the barring of UEs configured for Extended Access Barring,as described in TS 22.011 [67]. These mechanisms are further specifiedin TS 36.331 [37].

An eNB may initiate Extended Access Barring when: all the MMEs connectedto this eNB request to restrict the load for UEs that access the networkwith low access priority; or requested by O&M.

If an MME invokes the S1 interface overload procedure to restrict theload for UEs that access the network with low access priority, the MMEshould select all eNBs with which the MME has S1 interface connections.Alternatively, the selected eNBs may be limited to a subset of the eNBswith which the MME has S1 interface connection (e.g. particular locationarea or where devices of the targeted type are registered).

During an overload situation the MME should attempt to maintain supportfor emergency bearer services (see clause 4.3.12) and for MPS (seeclause 4.3.18).

When the MME is recovering, the MME can either: send, to some, or all,of the eNB(s), OVERLOAD START messages with new percentage value thatpermit more traffic to be carried, or the MME sends OVERLOAD STOPmessages to some, or all, of the eNB(s).

In addition, to protect the network from overload the MME has the optionof rejecting NAS request messages which include the low access priorityindicator before rejecting NAS request messages without the low accesspriority indicator (see clause 4.3.7.4.2 for more information) (Itcannot be guaranteed that voice services will be available for mobileterminated calls while the Mobility Management back-off timer isrunning. It is recommended, that UEs requiring voice services are notconfigured for low access priority).

While various aspects and embodiments of the present disclosure havebeen described above, it should be understood that they have beenpresented by way of example only, and not limitation. Thus, the breadthand scope of the present disclosure should not be limited by any of theabove-described exemplary embodiments. Moreover, any combination of theelements described in this disclosure in all possible variations thereofis encompassed by the disclosure unless otherwise indicated herein orotherwise clearly contradicted by context.

Additionally, while the processes described herein and illustrated inthe drawings are shown as a sequence of steps, this was done solely forthe sake of illustration. Accordingly, it is contemplated that somesteps may be added, some steps may be omitted, the order of the stepsmay be re-arranged, and some steps may be performed in parallel.

Advantages of this application includes, but are not limited to:

The advantage of this application is generally to provide rate control,congestion control, and/or flow control of UL data from a UE and DL datafrom a SCEF.

The advantage is to that the control plane of the 3GPP system is notoverloaded by CIoT devices (UEs) sending uplink small data, which couldhave severe effects on the system's ability to send control signalingbetween the MME and the UE and between the eNB and the UE. Further,using the SCEF means that DL transmission is blocked at the edge of the3GPP network when excessive DL data has been sent and rate control istriggered, thus not wasting any additional network resources.

The advantage is also that the rate control involves the UE (the CIoTdevice), that is, UL transmission is blocked in the UE when excessivedata has been sent and rate control is triggered, thus not wasting anyadditional radio resources.

The advantage is also that the control plane of the 3GPP system is notoverloaded by Servers on the Internet or Packet Data Networks (PDNs)sending downlink small data to CIoT devices (UEs), which could havesevere effects on the system's ability to send control signaling betweenthe MME and the UE and between the eNB and the UE.

Concise Description of Some Embodiments

1) Rate Control Method Performed by MME

In one aspect there is provided a rate control method performed by amobility management entity (MME). In one embodiment, the method includesthe MME receiving an uplink (UL) Non-Access Stratum (NAS) message (e.g.,attach request) transmitted by a wireless communication device (WCD).The method further includes the MME, after receiving the UL NAS message,generating a downlink (DL) NAS message and transmitting the DL NASmessage towards the WCD. The DL NAS message transmitted by the MMEcomprises information indicating a number of UL NAS messages containinguser data that the WCD is permitted send to the MME within a certaintime period.

In some embodiments, the number of UL NAS messages indicated by theinformation included in the DL NAS message is zero. In some embodiments,the DL NAS message transmitted by the MME comprises informationindicating the certain time period. In some embodiments, the UL NASmessage transmitted by the WCD comprises user data, and the methodfurther comprises the MME forwarding the user data to another device. Insome embodiments, the method further includes the MME receiving a secondUL NAS message transmitted by the WCD, wherein the second UL NAS messagecomprises user data intended for another device; and the MME discardingthe user data such that the MME does not forward the user data to theanother device.

2) Another MME Method

In another aspect there is provided a method performed in a mobilitymanagement entity (MME) node for managing signaling congestion. In oneembodiment the method includes the MME node receiving (e.g., accepting)a first control plane message (e.g., a non-access stratum (NAS) message,such as a NAS attach request message) transmitted by the WCD, the firstcontrol plane message including uplink (UL) data (e.g., user plane data)intended for relay by the MME node to another device. The method alsoincludes after receiving the first control message, the MME nodecreating a second control message (e.g., a NAS attach accept message),the second control plane message identifying at least one of: i) athrottling factor that indicates a level by which the WCD should reducethe amount of UL data in any future control plane message to the MMEnode, and ii) a throttling delay that indicates how much time the WCDshould wait before including any UL data in any future control planemessage to the MME. The method further includes the MME nodetransmitting the second control plane message including the at least oneof the throttling factor and the throttling delay, the second controlplane message intended for the WCD.

In some embodiments, the method further comprises the MME nodedetermining whether congestion of control signaling between the MME nodeand the WCD has deteriorated past a predetermined threshold, wherein thestep of transmitting the second control plane message including thethrottling factor or the throttling delay is performed in response toreceiving first control plane message from the WCD and determining thatcongestion has deteriorated past the predetermined threshold.

In some embodiments, the method further comprises the MME nodedetermining whether the WCD has exceeded a predetermined maximum dataquota or maximum data rate, wherein the step of transmitting the secondcontrol plane message including the throttling factor or the throttlingdelay is performed in response to receiving first control plane messagefrom the WCD and determining that the WCD has exceeded a predeterminedmaximum data quota or maximum data rate.

In some embodiments, the method further comprises, after transmittingthe second control plane message, the MME node transmitting a thirdcontrol plane message which includes no throttling factor and nothrottling delay, wherein the omission of the throttling factor and thethrottling delay is an indication that the one or more WCDs can stopthrottling UL data in control plane messages.

In some embodiments, the method further comprises the MME node, aftertransmitting the second control plane message, the MME node transmittinga third control plane message which includes another throttling factoror another throttling delay, wherein the other throttling delayoverrides the throttling delay in the second control plane message andthe other throttling factor overrides the throttling factor in thesecond control plane message.

In some embodiments, the throttling factor indicates that the WCDsshould include no UL data in any future control plane message to the MMEnode until the MME node indicates stopping of throttling.

In some embodiments, the method further comprises the MME nodedetermining a maximum bit rate (MBR) at which to limit UL data in thecontrol plane between the MME node and one or more WCDs attached to theMME node; and the MME determining the throttling factor or thethrottling delay based on the determined MBR.

In some embodiments, the control plane message is a non-access stratum(NAS) message transmitted as a payload by the WCD to a eNB in a RRCmessage and relayed from the eNB to the MME node as a payload in anuplink S1-AP message.

3) Method Performed by WCD

In another aspect, there is provided a method performed in a wirelesscommunication device (WCD) for managing signaling congestion. In someembodiments, the method includes the WCD transmitting a first controlplane message which includes uplink (UL) data intended for relay by amobility management entity (MME) node to another device, the firstcontrol plane message intended for the MME node. The method furtherincludes the WCD receiving a second control plane message transmittedfrom a mobility management entity (MME) node. The second control planemessage includes at least one of: i) a throttling factor that indicatesa level by which the WCD should reduce the amount of UL data in anyfuture control plane message to the MME node and ii) a throttling delaythat indicates how much time the WCD should wait before including any ULdata in any future control plane message to the base station or to theMME. The method further includes, after receiving the second controlplane message, the WCD transmitting a third control plane message withan amount of UL data (e.g., zero amount of UL data) based on thethrottling factor, or with zero amount of UL data if the a timer setbased on the throttling delay has not yet expired, the third controlplane message intended for the MME node.

In some embodiments, the method further includes, after receiving thesecond control plane message, the WCD receiving a third control planemessage transmitted from the MME node, the third control plane messageincluding no throttling factor and no throttling delay; and afterreceiving the third control plane message, the WCD transmitting towardthe MME node a fourth control plane message that includes UL data, theamount of UL data not being based on any throttling factor or anythrottling delay.

In some embodiments, the method further includes, after receiving thesecond control plane message, the WCD receiving a third control planemessage transmitted from the MME node, the third control plane messageincluding another throttling factor or another throttling delay, whereinthe other throttling delay overrides the throttling delay in the secondcontrol plane message and the other throttling factor overrides thethrottling factor in the second control plane message.

4) Method Performed by MME Linked to a SCEF

In another aspect, there is provided a method performed in a mobilitymanagement entity (MME) node linked to a service capability exposurefunction (SCEF) node and to one or more wireless communication devices(WCDs). In one embodiment, the method includes the MME node determiningwhether one or more throttling criteria have been met (e.g., whethercongestion of control signaling between the MME node and the one or moreWCDs has deteriorated past a predetermined threshold). The methodfurther includes, in response to determining that the one or morethrottling criteria have been met (e.g., congestion of control signalinghas deteriorated past the predetermined threshold): the MME nodecreating a first data delivery message (e.g., MT NIDD response or NIDDsubmit downlink ack message) that includes at least one of: i) athrottling factor that indicates a level by which the SCEF node shouldreduce the number of downlink (DL) data delivery requests to the MMEnode, and ii) a throttling delay that indicates how much time the SCEFnode should wait before transmitting any future data delivery request tothe MME node. The method further includes the MME node transmitting thefirst data delivery message including the at least one of the throttlingfactor and the throttling delay, the first data delivery messageintended for the SCEF node.

In some embodiments, the throttling factor or the throttling delay inthe first data delivery message applies to requests from the SCEF thatinclude non-internet-protocol (non-IP) data to be delivered to one ofthe one or more WCDs.

In some embodiments, the first data delivery message is a mobileterminated (MT) non-IP data delivery (NIDD) acknowledgement message andthe DL data delivery requests being throttled are MT NIDD deliveryrequests that include DL data for the one or more WCDs.

In some embodiments, the method further includes receiving a previousdata delivery request from the SCEF, wherein the step of transmittingthe first data delivery message is in response to determining thatcongestion has deteriorated past the predetermined threshold and toreceiving the previous data delivery request.

In some embodiments, the method further includes the MME node, aftertransmitting the first data delivery message including the at least oneof the throttling factor and the throttling delay, transmitting a seconddata delivery message which includes no throttling factor and nothrottling delay, wherein the omission of the throttling factor and thethrottling delay is an indication that the SCEF node can stop throttlingdata delivery requests to the MME node.

In some embodiments, the method further includes the MME node, aftertransmitting the first data delivery message including the at least oneof the throttling factor and the throttling delay, transmitting a seconddata delivery message which includes another throttling factor oranother throttling delay, wherein the other throttling factor overridesthe throttling factor in the first data delivery message and the otherthrottling delay overrides the throttling delay in the first datadelivery message.

In some embodiments, the method further includes the MME nodedetermining a maximum bit rate (MBR) at which to limit DL data in thecontrol plane between the MME node and the one or more WCDs; and the MMEdetermining the throttling factor or the throttling delay based on thedetermined MBR.

5) A Method Performed by a SCEF

In another aspect, there is provided a method performed in a serviceexposure capability function (SCEF) node. In one embodiment the methodincludes the SCEF receiving a first data delivery message (e.g., NIDDsubmission ack message or MT NIDD response message) transmitted by amobility management entity (MME) node, the first data delivery messageincluding at least one of: i) a throttling factor that indicates a levelby which the SCEF node should reduce the number of downlink (DL) datadelivery requests to the MME node, and ii) a throttling delay thatindicates how much time the SCEF node should wait before transmittingany future data delivery request to the MME node. The method furtherincludes after receiving the second control plane message, the SCEFreducing the number of data delivery requests transmitted to the MMEnode based on the throttling factor, or refraining from transmitting anydata delivery request to the MME node if a timer based on the throttlingdelay has not yet expired.

In some embodiments, the method further includes, after receiving thefirst data delivery message, the SCEF node receiving a second datadelivery message from the MME node that includes no throttling factorand no throttling delay; and after receiving the second data deliverymessage, the SCEF node stopping throttling of data delivery requests tothe MME node.

In some embodiments, the method further includes, after receiving thefirst data delivery message, the SCEF node receiving a second datadelivery message transmitted from the MME node, the second data deliverymessage including another throttling factor or another throttling delay,wherein the other throttling delay overrides the throttling delay in thefirst data delivery message and the other throttling factor overridesthe throttling factor in the first data delivery message.

6) Another Method Performed by MME

In another aspect, there is provided a method performed in a mobilitymanagement entity (MME) node for managing signaling congestion, the MMEnode adapted to exchange control signaling with one or more wirelesscommunication devices (WCDs) via a base station. The method includes theMME node determining whether congestion of control signaling between theMME node and the one or more WCDs has deteriorated past a predeterminedthreshold. The method further includes, in response to determining thatcongestion has deteriorated past the predetermined threshold, the MMEgenerating an overload start message that indicates the base stationshould reject any radio resource control (RRC) connection requests beingused by a WCD to access the MME node to send uplink (UL) data in acontrol plane message. The method further includes the MME nodetransmitting the overload start message toward the base station. In someembodiments, the overload control plane message applies to RRCconnection requests being used by a WCD to access the MME node to sendUL data having a normal priority level.

9) Base Station Method

In another aspect, there is provided a method performed in a basestation for managing signaling congestion, the base station linked to aMME node and one or more wireless communication devices (WCDs). Themethod includes the base station receiving an overload start messagetransmitted by the MME node, the message indicating the base stationshould reject any radio resource control (RRC) connection requests beingused by a WCD to access the MME node to send uplink (UL) data in acontrol plane message; after receiving the overload start message, thebase station receiving a RRC connection request from one of the WCDs,the RRC connection request including a control plane message; the basestation determining whether the control plane message includes UL data;and in response to determining that the control plane message includesUL data, the base station rejecting the RRC connection request.

10) Another MME Method

In another aspect, there is provided a method performed in a mobilitymanagement entity (MME) node for managing signaling congestion. Themethod includes the MME node determining whether one or more throttlingcriteria have been met; in response to determining that the one or morethrottling criteria has been met, the MME node creating a controlmessage (e.g., a NAS attach accept message), the control plane messageidentifying at least one of: i) a throttling factor that indicates alevel by which the WCD should reduce the amount of UL data in any futurecontrol plane message to the MME node, and ii) a throttling delay thatindicates how much time the WCD should wait before including any UL datain any future control plane message to the MME; and the MME nodetransmitting the control plane message including the at least one of thethrottling factor and the throttling delay, the control plane messageintended for the WCD. In some embodiments, the one or more throttlingcriteria includes at least one of: i) congestion of control signalingbetween the MME node and the WCD has deteriorated past a predeterminedthreshold; and ii) the WCD has exceeded a predetermined maximum dataquota or maximum data rate.

11) Another WCD Method

In another aspect, there is provided a method performed in a wirelesscommunication device (WCD) for managing signaling congestion. The methodincludes the WCD receiving a first control plane message transmittedfrom a mobility management entity (MME) node, the first control planemessage including at least one of: a throttling factor that indicates alevel by which the WCD should reduce the amount of UL data in any futurecontrol plane message to the MME node and ii) a throttling delay thatindicates how much time the WCD should wait before including any UL datain any future control plane message to the base station or to the MME,wherein the first control plane message is transmitted in response toone or more throttling criteria having been met. The method furtherincludes, after receiving the first control plane message, the WCDtransmitting a second control plane message with an amount of UL data(e.g., zero amount of UL data) based on the throttling factor, or withzero amount of UL data if the a timer set based on the throttling delayhas not yet expired, the second control plane message intended for theMME node.

12) Another MME Method

In another aspect, there is provided a method performed in a mobilitymanagement entity (MME) node linked to a service capability exposurefunction (SCEF) node and to one or more wireless communication devices(WCDs). The method includes the MME node receiving a first data deliveryrequest transmitted by the SCEF node, the first data delivery requestincluding DL data intended one of the one or more WCDs; after receivingthe first data delivery request, the MME node creating a first datadelivery response message that includes at least one of: i) a throttlingfactor that indicates a level by which the SCEF node should reduce thenumber of downlink (DL) data delivery requests to the MME node, and ii)a throttling delay that indicates how much time the SCEF node shouldwait before transmitting any future data delivery request to the MMEnode; and the MME node transmitting the first data delivery responsemessage including the at least one of the throttling factor and thethrottling delay, the first data delivery message intended for the SCEFnode.

13) Another MME Method

In another aspect, there is provided a method for CN overload control.In one embodiment, the method includes a network node (e.g., MME)determining that a load has reached a threshold. The method furtherincludes, after determining that the load has reached the threshold, thenetwork node transmitting to a base station an Overload Start messagecomprising information for configuring the base station such that thebase station rejects a request transmitted by a WCD for data transfervia control plane CIoT EPS Optimization.

14) Another Base Station Method

In another aspect, there is provided a method for CN overload control.In one embodiment, the method includes a base station receiving from anetwork node (e.g., MME) an Overload Start message comprisinginformation indicating that the base station may reject a request fordata transfer via control plane CIoT EPS Optimization. The methodfurther includes, after receiving the Overload Start message, the basestation receiving from a WCD a request for data transfer via controlplane CIoT EPS Optimization. The method further includes, in response toreceiving the request transmitted by the WCD, the base station rejectingthe request.

15) MME Node

In another aspect, there is provided a mobility management entity (MME)node comprising one or more processors configured for performing any oneof the MME methods disclosed herein.

16) WCD

In another aspect, there is provided a wireless communication device(WCD) comprising one or more processors configured for performing anyone of the WCD methods disclosed herein.

17) SCEF Node

In another aspect, there is provided a SCEF node comprising one or moreprocessors configured for performing any one of the SCEF methodsdisclosed herein.

18) Base Station

In another aspect, there is provided a base station comprising one ormore processors configured for performing any one of the base stationmethods disclosed herein.

1. A rate control method performed in a mobility management entity(MME), the method comprising: the MME receiving an uplink, (UL)Non-Access Stratum (NAS) message transmitted by a wireless communicationdevice (WCD); and the MME, in response to receiving the UL NAS message,generating a downlink (DL) NAS message and transmitting the DL NASmessage towards the WCD, wherein the DL NAS message transmitted by theMME comprises information indicating a number of UL NAS messagescontaining user data that the WCD is permitted send to the MME within acertain time period.
 2. The rate control method of claim 1, wherein thenumber of UL NAS messages indicated by the information included in theDL NAS message is zero.
 3. The rate control method of claim 1, whereinthe UL NAS message comprises an Attach Request.
 4. The rate controlmethod of claim 1, wherein the DL NAS message transmitted by the MMEcomprises information indicating the certain time period.
 5. The ratecontrol method of claim 1, wherein the UL NAS message transmitted by theWCD comprises user data, and the method further comprises the MMEforwarding the user data to another device.
 6. The rate control methodof claim 1, further comprising: the MME receiving a second UL NASmessage transmitted by the WCD, wherein the second UL NAS messagecomprises user data intended for another device; and the MME discardingthe user data such that the MME does not forward the user data to theanother device.
 7. A mobility management entity (MME) comprising: anetwork interface operable to receive an uplink (UL) Non-Access Stratum(NAS) message transmitted by a wireless communication device (WCD); anda data processing system comprising one or more processors, wherein thedata processing system is configured such that, in response to the MMEreceiving the UL NAS message, the data processing system: generates adownlink (DL) NAS message; and employs the network interface to transmitthe DL NAS message towards the WCD, wherein the DL NAS message comprisesinformation indicating a number of UL NAS messages containing user datathat the WCD is permitted send to the MME within a certain time period.8. The MME of claim 7, wherein the number of UL NAS messages indicatedby the information included in the DL NAS message is zero.
 9. The MME ofclaim 7, wherein the UL NAS message comprises an Attach Request.
 10. TheMME of claim 7, wherein the DL NAS message comprises informationindicating the certain time period.
 11. The MME of claim 7, wherein theUL NAS message transmitted by the WCD comprises user data, and the dataprocessing system is further configured to forward the user data toanother device.
 12. The MME of claim 7, wherein in response to the MMEreceiving a second UL NAS message transmitted by the WCD, wherein thesecond UL NAS message comprises user data intended for another device,the data processing system is configured to discard the user data suchthat the MME does not forward the user data to the another device.
 13. Amethod for core network (CN) overload control, the method comprising: anetwork node determining that a load has reached a threshold; and afterdetermining that the load has reached the threshold, the network nodetransmitting to a base station an Overload Start message comprisinginformation for configuring the base station such that the base stationrejects a request transmitted by a wireless communication device (WCD)for data transfer via control plane CIoT EPS Optimization.
 14. Themethod of claim 13, wherein the network node is a mobility managemententity.
 15. A mobility management entity (MME) comprising: a networkinterface operable to receive an uplink (UL) Non-Access Stratum (DL)message transmitted by a first wireless communication device (WCD); anda data processing system comprising one or more processors, wherein thedata processing system is configured such that, after determining that aload has reached a threshold, the data processing system: generates anOverload Start message; and employs the network interface to transmitthe Overload Start message to a base station, wherein the Overload Startmessage comprises information for configuring the base station such thatthe base station rejects a request transmitted by a WCD for datatransfer via control plane CIoT EPS Optimization.
 16. A method for corenetwork (CN) overload control, the method comprising: a base stationreceiving from a network node an Overload Start message comprisinginformation indicating that the base station may reject a request fordata transfer via control plane CIoT EPS Optimization; after receivingthe Overload Start message, the base station receiving from a WCD arequest for data transfer via control plane CIoT EPS Optimization; andin response to receiving the request transmitted by the WCD, the basestation rejecting the request.
 17. A base station comprising: atransceiver for transmitting data to wireless communication devices andfor receiving messages transmitted by the WCDs; a network interfaceoperable to receive an Overload Start message transmitted by a networknode, the Overload Start message comprising information for indicatingto the base station that the base station may reject a requesttransmitted by a WCD for data transfer via control plane CIoT EPSOptimization; and a data processing system comprising one or moreprocessors, wherein the data processing system is configured such that,after the base station receives the Overload Start message, the dataprocessing system configures the base station to reject a request fordata transfer via control plane CIoT EPS Optimization that was receivedfrom a WCD after the base station received the Overload Start message.